The propeller screw and its many modifications form the basis of most current fluid propulsion systems. Design and manufacture of the propeller screw requires mastery of foil dynamics in which profile, shape, area, angle, number of blades, and speed are important parameters. Moreover, the phenomena of cavitation and stall limit the performance of the majority of propeller screws. Propeller screws are also sometimes lethal to wildlife.
There is an effort to develop alternative propulsion systems in the form of reciprocating wings, with a promise of greater efficiency. Most engines in use today are of the reciprocating type, yet they are invariably used in rotary mode; the mechanical simplification afforded by direct drive of oscillating propulsion systems would be a major advantage. Reciprocating propulsion systems may also be better suited to harnessing wave power for propulsion, further increasing efficiency and helping to preserve the environment through reduced hydrocarbon use. Notwithstanding orientation, and based on mode of actuation, oscillating, planiform propulsion systems can be broadly summarized into rotative oscillation and translating oscillation. Rotative oscillation or fish tail type systems include systems wherein the fulcrum or center of rotation is located substantially at the leading edge of the blade and systems with the fulcrum located in an offset position, some distance down from the leading edge. Patents U.S. Pat. No. 4,214,547 to Hetland (1980), U.S. Pat. No. 4,894,032 to Sbrana (1990) illustrate rotative oscillation at the leading edge of the blade. Rotative oscillation from an offset fulcrum is illustrated for example in U.S. Pat. No. 6,250,585 to Pell (2001). Performance of these fish tail type propulsion systems is limited by the natural resonant frequency of materials used for construction, the thrust being reduced by the formation of standing waves at the resonant frequency; tuned compliant driveshafts have been described to overcome this limitation, at least up to 5 HZ, in U.S. Pat. No. 6,250,585 to Pell (2001).
Translating oscillation propulsion systems generally comprise a foil attached to a translating member; the foil is pivotally secured to the translating member so as to be positioned to the effective angle of attack by way of additional angling means. Angling means include movement range limiters and mechanical indexing linkage and positioning systems as illustrated, for example, in U.S. Pat. No. 4,102,293 to Geoffroy de la Roche (1978). U.S. Pat. No. 5,401,196 to Triantafyllou et al. (1995) and U.S. Pat. No. 4,371,347 to Jakobsen (1983). Current translating wing oscillation systems require many moving parts and are considered noisy and cumbersome. The complexity of the mechanisms required in current translating systems pose challenges to high speed operation. In addition, all current fluid propulsion systems act exclusively on fluids. Therefore it is an object and advantage of the Pulsed Locomotor to provide a simplified self adjusting propulsion system that can act on solid, liquid and gaseous media, without the need for angling devices in fluids.
The Pulsed Locomotor of the present disclosure can operate partially or fully submerged, and on land. The implement can be used as a fluid mixer and could be remotely actuated by electromagnetic fields much like a magnetic stir bar, propeller or the likes; it can also be used as a thruster in boating and swimming. The unique geometry and operation of the Pulsed Locomotor provide for cyclic acceleration and ejection of the ambient medium to produce thrust and enable displacement. In land based operation, the Pulsed Locomotor hops in discreet steps by leveraging or forcing against land or upon the ground.
It would be obvious to those skilled in the art that a reciprocation stroke length of 19 mm is employed in CA2854305, a parent application to the Pulsed Locomotor herein disclosed. Other objects and advantages of my invention will become apparent from the detailed description that follows and upon reference to the drawings.